When skiing, if the weather is good, I often come back with a better tan than if I have been at the beach. Obviously with altitude, there is less blocking of UV rays by the atmosphere.
But how much ...

All over the internet it says that sunscreen does not work all day, but does not say anything about why.
Why does sunscreen not work all day?
Does the matrials get destroyed by the UV rays? Or is it ...

I have a damaged pupil that stays partially dilated. And regular polarized sunglasses which I am wearing over the regular glasses aren't working better than my prescription sunglasses. I have a new ...

We drink water from PET bottles laying around on the soil (27° latitude, about 200 metres above sea level). They are filled with fresh water from a well and reused over and over again. We drink the ...

Is it a viable practice to not wear a shirt, as long as you smear your body with sunscreen if you plan to go hiking for hours(assuming reapplication)? Or is it advised to wear a shirt at all times and ...